c# - 用 Structuremap 装饰通用接口(interface)

Question

我有一个通用接口(interface)，它接受两个通用类型。我想装饰所有返回的版本，但由于我在调用 EnrichWith 时不知道类型，因此显然无法编译。我尝试使用在上下文中传递的 EnrichWith 重载，想也许我可以获取传入的泛型类型并调用 Activator.CreateInstance，但是在调试和检查上下文时上下文没有任何有用的信息。

这是我目前所拥有的。这是我的通用界面:

public interface IServiceOperation<in TRequest, out TResponse> where TResponse : ServiceResult, new()
{
    TResponse PerformService(TRequest validatedRequest);
}

这是一个示例实现:

public class SignUpService : IServiceOperation<SignUpRequest, SignUpResult>
{
    private readonly IUserRepository _userRepo;

    public SignUpService(IUserRepository userRepo)
    {
        _userRepo = userRepo;
    }

    public SignUpResult PerformService(SignUpRequest validatedRequest)
    {
        var user = Mapper.Map<User>(validatedRequest);

        user.MarkAsLoggedIn();
        user.ChangePassword(validatedRequest.UnhashedPassword);

        using(var transaction = _userRepo.BeginTransaction())
        {
            _userRepo.Save(user);
            transaction.Commit();
        }

        return new SignUpResult();
    }
}

这是我的装饰器，它也接受另一项服务:

public class ValidateServiceDecorator<TRequest, TResponse> : IServiceOperation<TRequest, TResponse> where TResponse : ServiceResult, new()
{
    private readonly IServiceOperation<TRequest, TResponse> _serviceOperation;
    private readonly IValidationService _validationService;

    public ValidateServiceDecorator(IServiceOperation<TRequest, TResponse> serviceOperation,
        IValidationService validationService)
    {
        _serviceOperation = serviceOperation;
        _validationService = validationService;
    }

    public TResponse PerformService(TRequest request)
    {
        var response = new TResponse();
        var validationResult = _validationService.Validate(request);

        if (!validationResult.IsValid)
        {
            response.ValidationErrors = validationResult.ValidationErrors;
            return response;
        }

        return _serviceOperation.PerformService(request);
    }

最后，这是我的容器已经走了多远。这显然无法编译，但 EnrichWith 行显示了我想要实现的目标:

public class StructureMapServiceScanner : Registry
{
    public StructureMapServiceScanner()
    {
        Scan(scanner =>
                {
                    scanner.AssemblyContainingType(typeof (IServiceOperation<,>));
                    scanner.ConnectImplementationsToTypesClosing(typeof (IServiceOperation<,>));
                });

        For(typeof (IServiceOperation<,>))
        .EnrichWith((ioc, original) => new ValidateServiceDecorator(original, ioc.GetInstance<IValidationService>()));
    }
}

因为这个问题需要更多的代码，下面是我试图通过的测试:

[TestClass]
public class StructureMapServiceScannerSpecs
{
    [TestMethod]
    public void Test()
    {
        ObjectFactory.Configure(cfg =>
                                    {
                                        cfg.AddRegistry<StructureMapServiceScanner>();
                                        cfg.For<IUserRepository>().Use(new Mock<IUserRepository>().Object);
                                        cfg.For<IValidationService>().Use(new Mock<IValidationService>().Object);
                                    });

        var service = ObjectFactory.GetInstance<IServiceOperation<SignUpRequest, SignUpResult>>();

        service.ShouldNotBeNull();
        service.ShouldBeType<ValidateServiceDecorator<SignUpRequest, SignUpResult>>();
    }
}

我觉得这应该很简单，而且我真的缺少一些关于如何使用 StructureMap 的东西。我可以为请求和响应类型的所有组合创建类型特定的版本，但显然这是不可取的。那我错过了什么？

Answer 1

最终能够弄清楚。我创建了一个 RegistrationConvention:

public class ServiceRegistrationConvention : IRegistrationConvention
{
    public void Process(Type type, Registry registry)
    {
        var interfacesImplemented = type.GetInterfaces();

        foreach (var interfaceImplemented in interfacesImplemented)
        {
            if (interfaceImplemented.IsGenericType && interfaceImplemented.GetGenericTypeDefinition() == typeof(IServiceOperation<,>))
            {
                var genericParameters = interfaceImplemented.GetGenericArguments();
                var closedValidatorType = typeof(ValidateServiceDecorator<,>).MakeGenericType(genericParameters);

                registry.For(interfaceImplemented)
                    .EnrichWith((context, original) => Activator.CreateInstance(closedValidatorType, original,
                                                                                context.GetInstance<IValidationService>()));
            }
        }
    }
}